From 295e3d222ca5da4d2f8faf080265bac175c6f6d1 Mon Sep 17 00:00:00 2001
From: Steven Watanabe <steven@providere-consulting.com>
Date: Wed, 14 Dec 2011 21:49:34 +0000
Subject: [PATCH] Fix the result of while.

[SVN r75945]
---
 src/engine/function.c       |  2 ++
 test/core-language/test.jam | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/engine/function.c b/src/engine/function.c
index b871f2c37..e5b4dd4c0 100644
--- a/src/engine/function.c
+++ b/src/engine/function.c
@@ -2192,6 +2192,8 @@ static void compile_parse( PARSE * parse, compiler * c, int result_location )
         int nested_result = result_location == RESULT_NONE? RESULT_NONE : RESULT_RETURN;
         int test = compile_new_label( c );
         int top = compile_new_label( c );
+        /* Make sure that we return an empty list if the loop runs zero times. */
+        adjust_result( c, RESULT_NONE, nested_result );
         /* Jump to the loop test */
         compile_emit_branch( c, INSTR_JUMP, test );
         compile_set_label( c, top );
diff --git a/test/core-language/test.jam b/test/core-language/test.jam
index 6b8b307bb..852d5d98a 100644
--- a/test/core-language/test.jam
+++ b/test/core-language/test.jam
@@ -1166,6 +1166,23 @@ rule test-rule
 
 check-equal while-result : [ test-rule ] : x ;
 
+rule test-rule
+{
+    local value = 1 2 ;
+    while $(value)
+    {
+        value = $(value[2-]) ;
+        local inner = $(value) ;
+        while $(inner)
+        {
+            inner = $(inner[2-]) ;
+            return x ;
+        }
+    }
+}
+
+check-equal while-result-2 : [ test-rule ] : ;
+
 }
 
 #